New actinolepid arthrodires from the Lower Devonian of Qujing, Yunnan, southwestern China

doi:10.19615/j.cnki.2096-9899.260908

Abstract

Abstract:

Here we describe new arthrodires (stem-Gnathostomata, Placodermi), Cuanyu liui gen. et sp. nov., and Cuanyu sp., from the Lochkovian (Xitun Formation, Lower Devonian) of Qujing, Yunnan, southwestern China. The new genus resembles other actinolepid arthrodires in the general arrangement of the skull roof plates, the ornamentation, and the sensory line pattern. Furthermore, it displays a single fused preorbital plate, a diagnostic feature of the family Actinolepidae. Cuanyu differs from other members of the Actinolepidae in possessing a deeply embayed posterior margin of the skull roof. The phylogenetic analysis supports its position within a monophyletic Actinolepidae, as the sister group of Szelepis. As one of the earliest arthrodires, Cuanyu is informative in revealing the character transformation in the early evolution of this diverse group of jawed vertebrates.

Key words: Qujing, Yunnan, Lower Devonian, Actinolepidae, Arthrodira, phylogeny

摘要：

记述了发现于中国云南曲靖下泥盆统洛赫考夫阶(西屯组)的节甲鱼类(有颌类干群，盾皮鱼纲)一新属——爨鱼(Cuanyu gen. nov.), 包括模式种刘氏爨鱼(Cuanyu liui gen. et sp. nov.)及其未定种(Cuanyu sp.)。新属具有与其他辐纹鱼类相似的特征，包括颅顶甲骨片的排列方式、表面纹饰和感觉沟模式。此外，新属具有辐纹鱼科的鉴定特征——愈合的眶前片，但其颅顶甲后缘的深凹等特征明显区别于其他辐纹鱼科成员。系统发育分析支持爨鱼属于辐纹鱼科，与斯氏鱼(Szelepis)构成姐妹群。作为目前所知最古老的节甲鱼类之一，爨鱼揭示了早期节甲鱼类的多样性，并为早期节甲鱼类特征演化提供了重要信息。

关键词: 云南曲靖, 下泥盆统, 辐纹鱼科, 节甲鱼目, 系统学

CLC Number:

Q915.862

WEN Yuan, ZHU Min, XUE Qin-Yuan, LI Qiang, ZHU You-An. New actinolepid arthrodires from the Lower Devonian of Qujing, Yunnan, southwestern China. Vertebrata Palasiatica, 2026, 64(4): 301-316.

文源, 朱敏, 薛钦元, 李强, 朱幼安. 2026, 64(4): 301-316, 云南曲靖早泥盆世辐纹鱼类一新属. 古脊椎动物学报.

Figures/Tables 6

Fig. 1 Photographs (A, C) and line drawings (B, D) of the holotype of Cuanyu liui gen. et sp. nov. from the Lower Devonian (upper Lochkovian) Xitun Formation of Qujing, Yunnan A, B. the skull roof in dorsal view with part of the neurocranium exposed (IVPP V33795a); C, D. external mold of the skull roof (V33795b). Scale bars equal 5 mm

Fig. 2 Photographs (A, C) and line drawings (B, D) of Cuanyu liui gen. et sp. nov. from the Lower Devonian (upper Lochkovian) Xitun Formation of Qujing, Yunnan A, B. the skull roof in dorsal view with part of the neurocranium exposed (IVPP V33796a); C, D. external mold of the skull roof (V33796b). Scale bars equal 5 mm

Fig. 3 Photographs (A, C) and line drawings (B, D) of Cuanyu liui gen. et sp. nov. from the Lower Devonian (upper Lochkovian) Xitun Formation of Qujing, Yunnan A, B. the neurocranium in dorsal view with part of the skull roof remained (IVPP V33801a); C, D. the skull roof in visceral view with a little external mold of the skull roof (V33801b). Scale bars equal 5 mm

Fig. 4 Photograph (A) and line drawing (B) of Cuanyu sp., the skull roof in dorsal view with part of the neurocranium exposed (IVPP V33797), from the Lower Devonian (upper Lochkovian) Xitun Formation of Qujing, Yunnan Scale bar equals 5 mm

Fig. 5 Comparison of the profundus sensory lines in arthrodires A. Cuanyu liui gen. et sp. nov.; B. Szelepis yunnanensis, after Dupret et al., 2017; C. Kujdanowiaspis podolica, after Dupret, 2010; D. Erikaspis zychi, after Dupret et al., 2007; E. Bryantolepis brachycephala, from Denison, 1958; F. Heightingtonaspis anglica, from Dineley and Liu, 1984; G. Simblaspis cachensis, from Denison, 1958; H. Aleosteus eganensis, after Johnson, 2000. Not to scale

Fig. 6 Strict consensus tree of 42 most parsimonious trees, based on a character dataset with 77 characters and 42 taxa (tree length = 201, consistency index = 0.378, retention index = 0.703)

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